Digital cameras using plural imaging units are known. The digital camera or multi-eye camera obtains plural images with parallax and combines them into a stereoscopic (stereo) image or 3-D image in which illusion of depth is created. During image capture using such a digital camera, camera shake causes parallax deviations. To prevent such parallax deviations in stereo images, in Japanese Patent Laid-Open Publication No. 2003-092768, amounts of movements in plural images obtained with each of image units are calculated, and then each image is trimmed in accordance with the calculated amounts of movements.
However, the above described method results in poor pixel efficiency because apart of pixels is inevitably trimmed in each image, and therefore a stereo image using all the pixels obtained with imaging elements cannot be generated. Additionally, amounts to be trimmed vary according to the amounts of movements. As a result, the size of the generated stereo image may also differ from that intended.
To solve such problems, it is devised to provide an optical image stabilization mechanism or optical camera shake correction mechanism in each of the imaging units (see Japanese Patent Laid-Open Publications No. 11-183951 and No. 2002-359768). The optical image stabilization mechanism moves a shake correcting section or image stabilizing section, e.g. an image sensor or a correction lens, to physically adjust the optical axis. Thereby, parallax deviations caused by the camera shake are prevented. Trimming of the images obtained with the imaging units is no longer necessary. As a result, a stereo image using all the pixels is generated without unintended changes in the size of the stereo image.
For the optical image stabilization, it is required to return each of the shake correcting sections to a reference position (home position), e.g. an optical axis of the imaging unit, when the shake correcting section reaches an edge of a corresponding correctable area or the stereo camera is in the pan/tilt state, or when the power is turned on. In a case where the stereo camera uses an optical image stabilization mechanism, positions of the shake correcting sections during the shake correction may vary from each other. The shake correcting sections may return to their respective reference positions with different timings. As a result, a length of a stereo base may change, which causes the parallax deviations (errors in stereo matching). Such parallax deviations differ from those caused by operations of a user, e.g. camera shake, which may annoy the user in observing the stereo image.